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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN">
<html><head><title>Ppmtosixel User Manual</title></head>
<body>
<h1>ppmtosixel</h1>
Updated: 1 August 2023
<br>
<a href="#index">Table Of Contents</a>
<h2>NAME</h2>
ppmtosixel - convert a PPM image to DEC sixel format
<h2 id="synopsis">SYNOPSIS</h2>
<b>ppmtosixel</b>
[<b>-raw</b>]
[<b>-margin</b>]
[<b>-7bit</b>]
[<i>ppmfile</i>]
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p><b>ppmtosixel</b> reads a PPM image as input and produces sixel
commands (SIX) as output. The output is formatted for color printing
(e.g. for a DEC LJ250 color inkjet printer) or for color display on
DEC VT terminals and terminal emulators (VT240 and beyond).
<p>If RGB values from the PPM file do not have maxval=100,
<b>ppmtosixel</b> rescales them to maxval 100. A printer control
header and a color assignment table begin the SIX file. Image data is
in a compressed format by default. A printer control footer ends the
image file.
<h2 id="options">OPTIONS</h2>
<p>In addition to the options common to all programs based on libnetpbm
(most notably <b>-quiet</b>, see <a href="index.html#commonoptions">
Common Options</a>), <b>ppmtosixel</b> recognizes the following
command line options:
<dl compact>
<dt><b>-raw</b>
<dd>If you specify this, each pixel will be explicitly described in
the image file. If <b>-raw</b> is not specified, output will default
to compressed format in which identical adjacent pixels are replaced
by "repeat pixel" commands. A raw file is often an order of
magnitude larger than a compressed file and prints much slower.
<dt><b>-margin</b>
<dd>If you don't specify <b>-margin</b>, the image will start at the
left margin (of the window, paper, or whatever). If you do
specify <b>-margin</b>, a 1.5 inch left margin will offset the image.
<dt><b>-7bit</b>
<dd>If you don't specify <b>-7bit</b>, each control code will be
expressed as a single, 8-bit "C1" character. If you do
specify <b>-7bit</b>, each control code will be expressed using two,
7-bit "C0" characters.
(See <a href="https://en.wikipedia.org/wiki/C0_and_C1_control_codes">C0
and C1 control codes</a> for more information.) In other
words, <b>-7bit</b> produces more portable sixel files, and its
absence produces smaller sixel files.
<p>This option was new in Netpbm 11.04 (September 2023).
</dl>
<h2 id="printing">PRINTING</h2>
<p>Generally, sixel files must reach the printer unfiltered.
Use the lpr -x option or <b>cat filename > /dev/tty0?</b>.
<h2 id="limitations">LIMITATIONS</h2>
Upon rescaling, truncation of the least significant bits of RGB values
may result in poor color conversion. If the original PPM maxval was
greater than 100, rescaling also reduces the image depth. While the
actual RGB values from the ppm file are more or less retained, the
color palette of the LJ250 may not match the colors on your screen.
This seems to be a printer limitation.
<h2 id="seealso">SEE ALSO</h2>
<a href="ppm.html">ppm</a>
<h2 id="author">AUTHOR</h2>
Copyright (C) 1991 by Rick Vinci.
<hr>
<h2 id="index">Table Of Contents</h2>
<ul>
<li><a href="#synopsis">SYNOPSIS</a>
<li><a href="#description">DESCRIPTION</a>
<li><a href="#options">OPTIONS</a>
<li><a href="#printing">PRINTING</a>
<li><a href="#limitations">LIMITATIONS</a>
<li><a href="#seealso">SEE ALSO</a>
<li><a href="#author">AUTHOR</a>
</ul>
</body>
</html>
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